Prepare Pastry: Unroll one puff pastry sheet into the baking pan. Prick with a fork and sprinkle with sugar. Bake at 356°F (180°C) in a preheated convection oven for 15 mins. Let it cool.
2 rectangular puff pastry sheets, Granulated sugar
Make Pastry Cream: Warm milk with lemon zest in a pot. In another pot, whisk eggs, then add sugar and flour. Gradually pour in the warm milk, stirring constantly. Cook until thickened, then remove from heat and add vanilla extract. Cover with plastic wrap and chill in the refrigerator.
4 cups milk, Zest of 1 lemon, 4 eggs, ¾ cup sugar, 1⅛ cups all-purpose flour, Vanilla extract
Assemble Cake: Spread the cooled pastry cream over the baked pastry base.
Add Top Layer: Unroll the second pastry sheet, prick it, and place it over the cream. Trim and seal the edges, sprinkle with sugar, and bake for about 25 mins at 356°F (180°C).
Finish and Serve: Cut the cake into squares and serve on a beautiful tray. Enjoy!